Abstract

Research on biased information search consistently has shown that, after having made a decision, people prefer supporting to conflicting information. Whether confirmation bias occurs in group decision making and this confirmation bias is reduced by debiasing mechanism was examined in two experiments. Experiment 1 indicated that people prefer supporting information and that the strength of this confirmation bias is strongest in intermediate hypothesis groups and weakest in groups searching information simultaneously. Experiment 2 showed that confirmation bias in homogeneous groups is stronger than that in heterogeneous groups. The classification of homogeneity and heterogeneity is based on the use or nonuse of the devil`s advocacy technique. The results also showed that devil`s advocacy technique is an effective way to debias the confirmation bias. Higher confidence in homogeneous groups was identified as an important mediator.